Finance term
Tier 1 Capital
Also known as: Tier 1, core capital, CET1
Definition
Tier 1 capital is a bank's core equity capital — primarily common stock and retained earnings. Under Basel III, banks must maintain a minimum Tier 1 capital ratio of 6% of risk-weighted assets (RWA). Tier 1 capital directly determines a bank's capacity to absorb losses and extend credit.
Detailed explanation
Basel III distinguishes between 'core' (Tier 1) and 'supplementary' (Tier 2) capital. Tier 1 capital — specifically Common Equity Tier 1 (CET1) — consists of paid-in common stock, retained earnings, and accumulated other comprehensive income (AOCI), minus regulatory deductions (goodwill, intangibles above threshold, deferred tax assets). It represents the highest quality, most loss-absorbing capital.
Basel III minimum capital ratios: CET1 ≥ 4.5% of RWA. Tier 1 (CET1 + Additional Tier 1) ≥ 6% of RWA. Total Capital (Tier 1 + Tier 2) ≥ 8% of RWA. Plus a Capital Conservation Buffer of 2.5% CET1 above these minimums — banks that breach the buffer face restrictions on dividends and bonuses. Large US banks face additional GSIB surcharges.
To be classified as 'well-capitalized' under US bank regulation — the threshold for avoiding enhanced regulatory scrutiny and deposit insurance premium increases — a bank needs: CET1 ≥ 6.5%, Tier 1 ≥ 8%, Total Capital ≥ 10%. Most healthy US banks maintain ratios well above these minimums as a buffer.
For borrowers, Tier 1 capital ratios are a proxy for a bank's lending capacity and financial health. A well-capitalized bank (high Tier 1 ratio) has more flexibility to extend credit, price competitively, and absorb credit losses. Banks approaching minimum capital ratios reduce lending, tighten credit standards, and focus on capital preservation. Monitoring your primary bank's capital ratios through their public filings provides early warning of potential credit tightening. Source: FDIC at https://www.fdic.gov/bank/individual/financial/.
◈ Worked example
- Tier 1 ratio calculation: Bank has $100B in risk-weighted assets. Tier 1 capital = $9B. Tier 1 ratio = 9% — above the 6% minimum and the 8% 'well-capitalized' threshold. Bank has $3B in excess Tier 1 capital above well-capitalized threshold, representing significant capacity for additional lending and loss absorption.
- Capital constraint on SMB lending: Bank's CET1 ratio = 7%. Conservation buffer = 4.5% + 2.5% = 7% minimum before restrictions. Bank is at minimum buffer — any new high-RWA (100%) SMB loans consume CET1 rapidly. Bank's credit committee tightens commercial underwriting, reduces SMB approval rates to preserve capital ratio. This is a direct transmission channel from bank capital stress to SMB credit access.
- SBA loan capital advantage: $1M SBA 7(a) loan (75% guaranteed) = $250K unguaranteed portion at 100% RWA = $250K RWA. At 6% Tier 1 minimum: $15K Tier 1 capital required. Same $1M conventional SMB loan: $1M RWA, $60K Tier 1 capital required. SBA loan uses 75% less Tier 1 capital — bank can make 4× more SBA loans than equivalent conventional loans on the same capital base.
Common questions
The most-asked questions about Tier 1 Capital — answered straightforwardly.
What is the difference between Tier 1 and Tier 2 capital? +
Tier 1 capital is 'core' capital — common stock, retained earnings. It is loss-absorbing on a going-concern basis (the bank is still operating). Tier 2 capital is 'supplementary' capital — subordinated debt, certain hybrid instruments, general loan loss provisions. Tier 2 capital absorbs losses primarily in bankruptcy/liquidation (gone-concern), not during ongoing operations. Total capital = Tier 1 + Tier 2, but Tier 1 is the more important and tightly regulated component.
How does a bank increase its Tier 1 capital ratio? +
Two levers: (1) increase the numerator — retain earnings (reduce dividends/buybacks), issue new common stock, raise other qualifying Tier 1 instruments; (2) decrease the denominator — reduce risk-weighted assets by shrinking the loan book, selling high-RWA assets, or shifting the portfolio toward lower-RWA assets (Treasuries, agency MBS). During financial stress, banks typically do both: raise capital and shrink RWA simultaneously.
Does my bank's Tier 1 capital ratio affect my loan application? +
Indirectly, yes. A bank with constrained Tier 1 capital will tighten credit standards, reduce approval rates, increase pricing, and restrict lending to higher-risk categories — including SMB loans (100% RWA). If you're seeing loan rejections or pricing increases from your bank, checking their public capital ratios (available in FDIC call reports) can reveal whether the bank is under capital pressure. Well-capitalized banks with Tier 1 ratios of 10%+ have significantly more lending flexibility.
Further reading
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